Civil Engineering Reference
In-Depth Information
•
Barrier coatings, 50 per cent successful
•
Hydrophobic coatings, 55 per cent successful
•
Other coatings, 26 per cent successful.
The poor success rate for other coatings can be attributed to factors such
as the use of aesthetic coatings in unsuitable situations.
The application of a coating over patches or injected cracks produced a
marked improvement in durability:
•
Patches were 30 per cent successful when solo and 50 per cent successful
when coated.
•
Crack injections were 70 per cent successful solo and 80 per cent
successful when coated.
Crack injection
The high success rate for crack injection (70 per cent) may be because it was
used in cases where corrosion was less advanced so that sealing the cracks
was sufficient to stop the process.
Cathodic protection
The CP data comprised 12 fully comprehensive case histories and 62
abbreviated cases. The performances of the 74 installations were as follows:
•
Wholly successful, 60 per cent
•
Requiring attention, 20 per cent
•
Failure, 20 per cent.
Restoration of strength
Restoration of strength was not always the main object of the repair as some
70 per cent of the problems also involved corrosion, many coupled with
frost damage. In this analysis the cases involving corrosion alone have been
excluded and the losses in strength were due to mechanical causes.
•
75 per cent of the repairs were successful.
14.5.3 Performance of repairs in relation to type of damage
Corrosion and AAR
It is evident from
Table 14.1
(p. 238) that it is particularly difficult to halt
the process of AAR and repair the damage successfully as only 20 per cent of
the repairs were successful.
